Sign holder



FIG. 1 is a front elevational view of a sign holder showing my new design, with the rear being a mirror image;

FIG. 2 is a side elevational view thereof, with the opposite side being a mirror image;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof; and,

FIG. 5 is a perspective view thereof, with the broken line showing for illustration purposes only and forming no part of the claimed design. 

The ornamental design for a sign holder, as shown and described. 